I have a 1989 Ford F250 that doesn't shift into high.

Need more info Auto trans??? The bands are adjustable and theres other concerns as well Vacum to the trans and possible Modulator problems, but first when was the filter changed ???

It is an automatic "sorry"hahaha it was my dad's I have only had it sense October and never had it on fwy till last week. I went 109 miles and used 18 gal. Of Gass never went over 55.

Wow! 109 miles on 18 gallons of gas! 6mpg... Thats less than what I get on my 65 Thunderbird 390 with 350 hp and I thought that 7 mpg was bad.

I'd change the filter and fresh Dexron Mercon Atf

Getting serious; you didn't say how many miles are on this truck but I would guess an 89' would have about 250k at 10k per year. That estimate is based on being driven every year. Also, you don't say if you have a 3 or 4 speed trans, if your truck is 2 or 4 wheel drive and if it is a 5.0 or 5.8 V8. With my crystal ball having fallen off the shelf awhile back, I am picking 2 wheel drive, 3-sp 5.8 CI. Accorrding to EPA it was rated at 10 city, 12 Hwy. If it wouldn't go into high and fluid is new and the correct type and the filter is clean then you either have a vacuum leak to the modulator valve, bad valve, loose or burned bands or a combination of any of them.

Thanks old timer I will give your answers a try and you must have found your ball all you guesses were on the money.

Keep me posted... thanks

Hey old timer where is the darn PCV valve on this motor it is the 7.8 I think the biggest one ford made this year. My dad said he has never changed it I think this might help with gas mileage issue.

I am not sure on the 7.8 but usually they are either on the valve cover, possibly in the air cleaner or on a hose going to it.

Larry, let me pick your brain on the same problem on a 1989 F-250 7.3L IDI. Have changed the AT filter and fluid, still feels like it is just getting to 2nd gear, and its slow getting to 2nd. Would it be the same things to check? Thanks.

Sounds like the same thing. If you let up on the gas will it shift then? That would be vacuum problem.

Have to let off the gas to go from first to second and that's as far as she'll go.

Check all vacuum lines and modulator valve on transmission

It's probably the right side plugin on the transmission. It's hard to get to it but that's what I had on my 1989 Ford f350 I unplugged all the plugins and clean them whit electrical cleaner and blow them dry and put some electric grees in plug them all back in. It works like New.. ol the best thanks...